Generally, the common input device of a computer system includes for example a mouse device, a keyboard device, a trackball device, or the like. Via the keyboard device, the user may input characters and symbols into the computer system. As a consequence, most users and most manufacturers of input devices pay much attention to the development of keyboard devices.
Hereinafter, the structures and the functions of a conventional keyboard device will be illustrated with reference to FIG. 1. FIG. 1 is a schematic view illustrating the outward appearance of a conventional keyboard device. As shown in FIG. 1, there are plural keys 10 and plural indicating lamps 11 on a surface of the conventional keyboard device 1. These keys 10 include ordinary keys, numeric keys, function keys, and the like. When one of these keys 10 is depressed by the user's finger, a corresponding signal is issued to the computer, and thus the computer executes a function corresponding to the depressed key. For example, when an ordinary key is depressed, a corresponding English letter or symbol is inputted into the computer. When a numeric key is depressed, a corresponding number is inputted into the computer. In addition, the function keys (F1˜F12) can be programmed to provide various functions. The locations of the indicating lamps 11 correspond to the Caps lock key, the Number lock key and the Scroll lock key, respectively. In case that one of the Caps lock key, the Number lock key and the Scroll lock key is depressed, a corresponding specific function is enabled, and thus a corresponding indicating lamp 11 is turned on to result in a prompt. According to the illuminated indicating lamp, the user may realize that the corresponding one of the Caps lock key, the Number lock key and the Scroll lock key has been depressed and the corresponding function has been enabled. Since these indicating lamps 11 occupy additional layout space of the keyboard device 1, the indicating lamps become hindrance from reducing the volume of the keyboard device 1. Moreover, too many indicating lamps 11 may confuse the user. Under this circumstance, the user fails to accurately judge which key is correlated to the illuminated indicating lamp.
For solving the above drawbacks, a keyboard device with a luminous key is disclosed. FIG. 2 is a schematic cross-sectional view illustrating a conventional keyboard device with a luminous key. As shown in FIG. 2, the keyboard device 2 comprises a base 20, plural luminous keys 21, plural non-luminous keys 22, plural light-emitting elements 23, a membrane switch circuit member 24, and a plastic film layer 25. Each of the luminous keys 21 comprises a keycap 211 and an elastic element 212. Each of the non-luminous keys 22 comprises a keycap 221 and an elastic element 222. The keycap 211 of each luminous key 21 has a light-transmissible zone 2111. The plural light-emitting elements 23 are disposed on the membrane switch circuit member 24 and disposed under the light-transmissible zone 2111 of corresponding luminous keys 21. The plural light-emitting elements 23 are used for emitting plural light beams (not shown). The light beams may be transmitted through the light-transmissible zones 2111 of the luminous keys 21. The luminous keys 21 are specific function keys, which may be triggered to enable specific functions. For example, the luminous keys 21 includes the Caps lock key, the Number lock key, the Scroll lock key, and the like. Each of the luminous keys 21 further comprises a light shade 213 with an opening 2131. In addition, the corresponding light-emitting element 23 is partially enclosed by the light shade 213. Consequently, the light beams emitted by the light-emitting element 23 are only permitted to be transmitted through the opening 2131 of the light shade 213 without being scattered through the periphery of the light shade 213. As shown in FIG. 2, the light-emitting elements 23 are top-view light emitting diodes. In addition, the light shade 213 is made of a rubbery material.
The membrane switch circuit member 24 comprises an upper wiring board 241, a partition plate 242, and a lower wiring board 243. The upper wiring board 241 has plural upper contacts 2411 corresponding to the plural luminous keys 21 and the plural non-luminous keys 22. The partition plate 242 is disposed under the upper wiring board 241. In addition, the partition plate 242 has plural perforations 2421 corresponding to the plural upper contacts 2411. The lower wiring board 243 is disposed under the partition plate 242. In addition, the lower wiring board 243 has plural lower contacts 2431 corresponding to the plural perforations 2421. Each of the upper contacts 2411, the corresponding perforation 2421 and the corresponding lower contact 2431 are collectively defined as a key intersection 244. The plastic film layer 25 is disposed on the membrane switch circuit member 24. In addition, the plastic film layer 25 is coated with a black ink layer 251, so that the light beams are blocked by the plastic film layer 25. The base 20 is used for supporting the plural luminous keys 21, the plural non-luminous keys 22, the plural light-emitting elements 23, the membrane switch circuit member 24 and the plastic film layer 25.
When the keycap 211 of the luminous key 21 or the keycap 221 of the non-luminous key 22 is depressed by the user, the keycap 211 or 221 is moved downwardly to compress the elastic element 212 or 222, so that the corresponding upper contact 2411 is pushed by the elastic element 212 or 222. Consequently, the corresponding upper contact 2411 is inserted into the corresponding perforation 2421 to be contacted with the corresponding lower contact 2431. When the upper contact 2411 and the lower contact 2431 are contacted with each other, the corresponding key intersection 244 is electrically conducted, and thus a corresponding luminous key signal or a corresponding non-luminous key signal is generated. On the other hand, when the depressing force exerted on the keycap 211 or 221 is eliminated, an elastic force provided by the elastic element 212 or 222 is acted on the keycap 211 or 221. In response to the elastic force, the keycap 211 or 221 is moved upwardly and returned to an original position where the keycap 211 or 221 is not depressed.
In addition, when the keycap 211 of one of the luminous keys 21 is depressed and a corresponding luminous key signal is generated, the specific function corresponding to the depressed luminous key 21 is enabled. At the same time, the corresponding light-emitting element 23 is driven to emit a light beam in response to the luminous key signal. The light beam will be sequentially transmitted through the opening 2131 of the light shade 213 and the light-transmissible zone 2111 of the keycap 211. Since the light shade 213 has a function of centralizing the light beam, the intensity of the light beam outputted from the light-transmissible zone 2111 of the keycap 211 is increased to facilitate the user to realize whether the specific function corresponding to the depressed luminous key 21 is enabled.
Since the light shades 213 of the luminous keys 21 are attached on the plastic film layer 25 by adhesion, some drawbacks may possibly occur. For example, during the process of attaching the light shade 213 on the plastic film layer 25, if the light shade 213 is suffered from misalignment, the opening 2131 of the light shade 213 fails to be aligned with the light-emitting element 23. Under this circumstance, only a portion of the light beam from the light-emitting element 23 is transmitted through the opening 2131 of the light shade 213. Whereas, the remaindering portion of the light beam from the light-emitting element 23 is blocked by the light shade 213. Consequently, the illuminating efficacy of the luminous key 21 is insufficient for the user to identify whether the luminous key 21 is illuminated. In addition, an assembling error is readily generated during the process of assembling the light shade 213 and the plastic film layer 25. Consequently, after the keyboard 2 is produced, the light shade 213 is easily detached. If the light shade 213 is detached, the light beam emitted by the light-emitting element 23 will be scattered everywhere because the light beam is no longer centralized by the light shade 213. Under this circumstance, the illuminating efficacy of the luminous key 21 is still insufficient.
For solving the above drawbacks, another keyboard device with a luminous key is introduced into the market. This keyboard device is equipped with a backlight module for emitting a light beam and guiding the light beam to an additional light-outputting zone of the keycap. For example, the additional light-outputting zone is a character region or a symbol region of the keycap. By means of the backlight module, the light beam can be directed to the additional light-outputting zone of the keycap in order to illuminate the character or the symbol. However, for preventing from light leakage, the backlight module should be equipped with a light shade, and the light shade should be securely fixed.